PROJECT SUMMARY Fifteen million babies are born preterm each year, of whom one million die within their first 28 days of life, making preterm birth the leading cause of death in neonates, infants and children under age 5. Moreover, premature infants who do survive often have lifelong physical disability and cognitive impairment. In the US, Black women are 1.5 times more likely to deliver preterm than women from other racial/ethnic groups. Nonetheless, despite years of research, little progress has been made in reducing preterm birth rates, and disparities are increasing. In view of these critical public health issues, the Pregnancy and Perinatology Branch at NICHD has included preterm birth and its consequences, perinatal health disparities, global perinatal health and elimination of neonatal pain among its 7 priority topics. The overarching goal of ?Transdisciplinary Research Training to Reduce Disparities in Preterm Birth and Improve Maternal and Neonatal Outcomes? is to train a cadre of investigators from a wide range of clinical specialties, scientific disciplines, and lived experiences who will be poised to engage in rigorous, transdisciplinary, collaborative efforts to 1) identify and elucidate the mechanisms by which biomedical, psychosocial, interpersonal and institutional factors increase the risk for preterm birth and associated adverse outcomes for infants, mothers, and families locally and globally; 2) develop, test and implement interventions to reduce the rate of preterm birth and associated adverse outcomes; and 3) eliminate disparities in preterm birth and adverse outcomes in this country. In 2014, with funding from the Bill & Melinda Gates Foundation and Marc and Lynne Benioff, UCSF established the Preterm Birth Initiative, an innovative, health-equity focused, transdisciplinary research program that takes a cell-to-society and life course approach to reduce the local and global burden of preterm birth. As part of that initiative, a pilot postdoctoral fellowship program was launched to train the next generation of scholars to tackle the vexing preterm birth epidemic in the US and globally. Nine fellows representing varied clinical specialties (obstetrics, neonatology, pediatric neurology and midwifery) and scientific disciplines (biology, anatomy, public health, psychology, sociology and epidemiology) have enrolled, and all of the graduates have gone on to faculty positions, primarily with funding from NIH K-level awards. The specific aim for this proposal is to build on the success of the pilot fellowship program and ensure its sustainability. We will recruit 12 postdoctoral fellows (3 per year for 4 years, with a balance of MDs and PhDs) and provide them with the resources and mentorship they need to develop into independently funded scientists working collaboratively to change the course on preterm birth. Fellows will work with mentorship teams to design and implement research projects and engage in weekly didactic activities to further their skills and experience in conducting transdisciplinary research. Program components will also include advanced courses in research methods and ethics, seminars and grand rounds, peer review activities, and paper/grant writing.